smb_addmsghdr() will now confirm the index file length against the

status.total_msgs value: if they don't match, don't add header & index
to the message base, it's apparently corrupted and we're only going to
make things worse as smb_putmsgidx() will fail (after we've stored the hdr)
with an "invalid index offset" error.

src/smblib/smblib.c

@@ -1529,6 +1529,7 @@ int SMBCALL smb_addmsghdr(smb_t* smb, smbmsg_t* msg, int storage)
 	int		i;
 	long	l;
 	ulong	hdrlen;
+	long	idxlen;
 
 	if(smb->shd_fp==NULL) {
 		safe_snprintf(smb->last_error,sizeof(smb->last_error),"%s msgbase not open", __FUNCTION__);
@@ -1551,6 +1552,16 @@ int SMBCALL smb_addmsghdr(smb_t* smb, smbmsg_t* msg, int storage)
 		smb_unlocksmbhdr(smb);
 		return(i);
 	}
+
+	idxlen = filelength(fileno(smb->sid_fp));
+	if(idxlen != (smb->status.total_msgs * sizeof(idxrec_t))) {
+		safe_snprintf(smb->last_error, sizeof(smb->last_error)
+			,"%s index file length (%ld) unexpected (%ld)", __FUNCTION__
+			,idxlen, smb->status.total_msgs * sizeof(idxrec_t));
+		smb_unlocksmbhdr(smb);
+		return SMB_ERR_FILE_LEN;
+	}
+		
 	msg->hdr.number=smb->status.last_msg+1;
 
 	if(msg->hdr.thread_id==0)	/* new thread being started */